Patent Application
20160046030
The present invention relates to a method for cutting or trimming a hollow object having one or more relatively thin walls, the method including an oscillation step that reduces wall deformation at the site of the initial cut to produce a relatively straight leading edge on the object, in combination with a further cutting step that does not include oscillation of a cutting blade. A second oscillation step can be performed after the non-oscillation step, as the cut begins to exit the part, that leads to the separation of the object into two pieces and also produces a relatively straight trailing edge. A device for performing the cutting methods is disclosed.
Hollow objects or parts having relatively thin walls, such as those formed from plastic, can be difficult to cut or trim to produce a finished part having a relatively straight edge. At the start of a cutting operation, when utilizing a knife or other cutting device with a fixed blade, the material of the object can deflect inwardly and away from the pressure exerted by the blade, generally until the blade enters the material. Once the blade has cut or been passed through a portion of the material, a straight-line cut can be produced until reaching the end point of the object at which time the material thereof may deflect outwardly, away from the cutting pressure, until the blade separates the object or article into two pieces. Thus, in some embodiments the finished part may have a cut-finished end with a scalloped appearance, wherein the leading edge and trailing edge of the object is longer than a central area.
Although various cutting devices are known to those of ordinary skill in the art, for example knives, saws, routers, hot knives, ultra sonic knives, and guillotines, the art still needs a method for cutting hollow, relatively thin-walled articles or objects that results in a finished product having a relatively straight edge.
In view of the above, it is an object of the present invention to provide a method for cutting or trimming a thin-walled, hollow object or article to produce a finished article having a relatively straight-edged surface.
Still another object of the present invention is to provide a process for cutting or trimming hollow plastic molded parts using at least two different cutting sequences including an oscillation step wherein a knife or blade, preferably having a straight, non-serrated edge, is oscillated while cutting through a portion of the article, thereby reducing or preventing distortion of the part, and a second step free of the oscillation during cutting.
Yet another object of the present invention is to provide an oscillation cutting step, wherein a knife or blade is oscillated during first contact of the knife or blade on an uncut hollow plastic part or object, wherein the oscillation occurs, generally transverse or perpendicular to a cutting axis in one embodiment, while the knife or blade is moved along the cutting axis and further into the part or object.
A further object of the present invention is provide a method which discontinues an oscillation of the knife or blade after the knife or blade has entered into the object a desired distance, wherein the knife or blade continues to cut the object as the knife or blade is moved along the cutting axis.
Still another object of the present invention is to perform a second oscillation step after a non-oscillation step as the knife or blade approaches an end of the object opposite the first end of the object first cut by the knife or blade. The second, further oscillation step is continued until the object is cut into two pieces or a desired cutting operation has otherwise been performed.
In a further aspect, the knife or blade can be oscillated during the entire cutting process.
In one aspect of the invention, a method for cutting an object having a wall and at least one hollow portion is disclosed, comprising the steps of obtaining the object; cutting the object using at least two different cutting sequences, including an oscillation step wherein a blade is oscillated while first contacting and cutting into a portion of the object followed by a second step of cutting the object without oscillating the blade.
In another aspect of the invention, a cutting method for objects having a hollow portion is disclosed, comprising the steps of: obtaining an object to be cut; obtaining a cutting device comprising a frame and a carriage movable in relation to the frame along a cutting axis, an oscillating device connected to the carriage and arranged to selectively oscillate the carriage on a second oscillating axis arranged from about 35° to 90° in relation to the cutting axis, and a cutting blade having a cutting edge for cutting the object; moving the carriage towards the object along the cutting axis and oscillating the cutting blade prior to and/or during first contact of the object with the cutting blade; and ceasing oscillation of the cutting blade after a period of time and continuing to cut the object with the cutting blade along the cutting axis.
In yet another aspect of the invention, a cutting device is disclosed, comprising a frame and a carriage movable in relation to the frame along a cutting axis, and oscillating device connected to the carriage and arranged to selectively oscillate the carriage on a second oscillating axis arranged at an angle of about 35° to 90° in relation to the cutting axis, and a cutting blade having a cutting edge for cutting the object operatively connected to the carriage.
The invention will be better understood and other features and advantages will become apparent by reading the detailed description of the invention, taken together with the drawings, wherein:
This description of preferred embodiments is to be read in connection with the accompanying drawings, which are part of the entire written description of this invention. In the description, corresponding reference numbers are used throughout to identify the same or functionally similar elements. Relative terms such as “horizontal,” “vertical,” “up,” “upper”, “down,” “lower”, “top” and “bottom” as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing figure under discussion. These relative terms are for convenience of description and are not intended to require a particular orientation unless specifically stated as such. Terms including “inwardly” versus “outwardly,” “longitudinal” versus “lateral” and the like are to be interpreted relative to one another or relative to an axis of elongation, or an axis or center of rotation, as appropriate. Terms concerning attachments, coupling and the like, such as “connected” and “interconnected,” refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. The term “operatively connected” is such an attachment, coupling or connection that allows the pertinent structures to operate as intended by virtue of that relationship.
The methods or processes of the present invention for cutting hollow, thin-walled objects or parts, such as plastic parts utilize two or more cutting steps in sequence, including a first cutting step wherein a straight, non-serrated knife or blade is oscillated in a direction other than along a cutting axis and contacted with a leading edge of the part at a location desired to be cut. The second cutting step is a non-oscillation cutting procedure that is performed by pushing or pulling the knife or blade through a portion of the part along the cutting axis after the first cutting step has been performed. In a preferred embodiment, a second oscillation cutting step is performed after the non-oscillation step as the knife or blade approaches a distal end of the part. The second oscillation step is continued until the part is cut into two pieces.
The methods of the present invention solve various problems of the prior art methods that are encountered when cutting an object or part into a final shape. Relatively thin-walled, hollow, plastic parts such as formed by blow molding, rotational molding or other process are only semi-rigid in some embodiments. When pressure from a knife or blade is exerted onto the outside of a hollow plastic part, the knife or blade can deform the part, sometimes to the extent that the part is no longer within manufacturing tolerances. The manufacturing tolerances may vary with different applications, but can be relatively small. The methods of the present invention provide an economical cutting process that reduces deformation of the plastic part and provides a straight or square edge to the finished part.
Referring now to the drawings,
A guide rail assembly 20 is connected to the frame 12 for moving carriage along a linear cutting axis 18. The cutting axis utilized allows the cutting knife or blade 60 to cut or trim a desired object or part into two or more separate pieces. Guide rail assembly 20 includes one or more guide rails 21 that direct carriage 30 along cutting axis 18 and engage with one or more carriage bearings 32 of carriage 30 that comprise linear bearings in one embodiment. Carriage bearings 32 provide low friction travel of the carriage 30 on the guide rail assembly 20.
A drive system 22, a screw drive in one embodiment, is present on the guide rail assembly. Drive system 22 includes a servo motor 23 operatively connected to a screw 24 that is connected to the guide rail assembly 20 by two bearings supports 25. A screw drive nut 27 operatively connected to screw 24 is connected to carriage 30, in one embodiment by connecting a suitable bracket between the screw drive nut 27 and carriage 30. The screw drive nut 27 drives the carriage 30 forward or backward along cutting axis 18 when the servo motor 23 is actuated.
A carriage mount plate 33 connected to carriage bearings 32 includes a carriage guide rail assembly 40, see
A cutting blade mount plate 36 is connected to oscillating axis bearings 35 and oscillating device 37, such as an air cylinder in one embodiment is connected to cutting blade mount plate 36. The oscillating device 37 includes an actuating rod 38 connected to an actuator end 39. The oscillating device 37 provides the oscillation by using two limit sensors, which sense the location of the cylinder. By using sensors, the frequency of the oscillation can be adjusted by moving the sensors. The oscillation process is started in one embodiment when the carriage 30 reaches a pre-programmed position along guide rail 21. Once this position is reached, the oscillation device 37 is activated, causing the carriage 30 to move to a second position, see
One or more arms 42 are connected to the cutting blade mount plate 36. The cutting knife or blade 60 is connected to arm 42. As illustrated in the figures, blade 60 is connected between two arms 42. Blade 60 has a cutting edge 62 that is linear in a preferred embodiment, and is situated at a desired angle with respect to cutting axis 18. The cutting knife or blade 60 can be connected to the arm 42 in a manner so that the cutting edge 62 has an axis that is situated at an angle of about 80° to about 110°, desirably from about 85° to about 105°, preferably from about 90° to about 100° in relation to the cutting axis 18. In one embodiment, the blade 60 has a cutting edge that has either a single bevel or double bevel in order to provide the desired cutting action. In one embodiment, the cutting edge 62 has an axis that is situated along axis 19 that is perpendicular to cutting axis 18. Blade 60 is connected to arms 42 utilizing any suitable method. For example, in one embodiment, the blade 60 is bolted to the blades, but obviously other fastener connections can be utilized.
Methods of utilizing the device of the present invention will now be explained utilizing
In various embodiments, the first oscillation step can be performed until the knife edge has entered the part reaching a point where the cutting direction is inline with the wall being cut. Cutting edge has cut through up to 45%, and desirably up to 20% of the length of article 80 measured along the cutting axis 18. Likewise, the second oscillation step can be initiated prior to 45%, and desirably less than 20% of the length of article 80 remaining to be cut along axis 18.
Utilizing the methods of the present invention, finished, hollow, articles having at least one open end are formed having a clean, substantially straight edge about the opening formed by the multiple step cutting methods of the present invention.
In accordance with the patent statutes, the best mode and preferred embodiment have been set forth; the scope of the invention is not limited thereto, but rather by the scope of the attached claims.
